At a glance
Symptoms
- • Strong sulfur, rotten-egg, or skunk-like smell near a gas appliance
- • Hissing sound near a gas line, valve, or appliance connection
- • Pilot light has gone out and the smell remains after a few minutes
- • Dead vegetation in a line over an underground gas pipe (outdoor)
- • Faint headache, dizziness, or nausea while in the room with the appliance
- • Gas detector or carbon monoxide detector alarm sounding
- • Visible damage to a flexible gas connector or rigid gas pipe
Common causes
- • Pilot light has been blown out, leaving raw gas escaping from an older non-safety-valved appliance
- • Failed or partially open gas valve on an appliance
- • Faulty pressure regulator
- • Damaged gas line — kink, crack, or corrosion at a fitting
- • Loose connection at the appliance shutoff or supply line
- • Brief mercaptan smell after relighting a pilot or starting a recently serviced appliance (this should clear within 1-2 minutes; if it persists, treat as a real leak)
- • Cracked heat exchanger on a furnace or water heater (combustion-gas leak — also produces carbon monoxide)
Safety First — Read Before You Start
- •DO NOT operate any electrical switch — light switches, fans, garage door openers, thermostats. The small spark from a switch is enough to ignite accumulated gas.
- •DO NOT use your phone inside the home. Phones can spark internally even with no visible activity. Take the phone outside before calling.
- •DO NOT light matches, lighters, candles, or any open flame. Do not smoke.
- •DO NOT start a car in an attached garage. The starter motor is a powerful spark source.
- •DO NOT plug in or unplug any appliance — outlet sparks ignite gas just as switches do.
- •DO NOT try to find the leak yourself. Even a small soap-bubble test belongs to a licensed tech who is wearing the right equipment and has the gas supply controlled.
- •DO NOT re-enter the home until the gas company or a licensed tech has confirmed it is safe.
Tools & supplies you'll need
- No tools — this is not a DIY situation
- Phone (used from outside the home, not inside)
- Gas company emergency line phone number
- Licensed gas technician contact
Step-by-step instructions
Recognize the smell and act immediately
Natural gas and propane are odorless on their own — the gas company adds a chemical called mercaptan that produces a strong rotten-egg or sulfur smell at very low concentrations, well below any explosion risk. If you smell that distinctive odor, treat it as gas regardless of how faint. The risk window between 'noticeable smell' and 'explosive concentration' can be short, especially in a closed room. Do not pause to investigate or to convince yourself it is something else. Your job from this moment is to leave the home safely.
⚠Warning: If you feel dizzy, lightheaded, or nauseous — leave immediately. Mercaptan does not cause those symptoms; gas accumulation does, and it means the concentration is already significant.
Open exterior doors and windows ONLY on your way out
As you leave the home, open exterior doors and windows in your immediate path to help vent the gas. Do not detour to open windows in distant rooms. Do not turn on bathroom or kitchen fans — those are electrical devices and can spark. The goal is to ventilate as you exit, not to clear the home before leaving. Time matters more than thoroughness.
Tip: If a window is jammed or you have to choose between opening one window and getting out faster, get out faster. The gas company will ventilate the home properly when they arrive.
Get everyone (and pets) out of the home
Take all family members, pets, and any guests out of the home. Walk to the sidewalk or another property at least 50-100 feet away. If you live in an attached unit, alert immediate neighbors and have them leave too — gas concentrations in shared walls and attics can spread between units. Do not stop to gather valuables, electronics, or non-essentials. A laptop is replaceable; the family is not.
âš Warning: Do not leave anyone behind to "investigate" or "check the kitchen one more time." A single light switch flip in a room with concentrated gas can level the home.
Call your gas company from outside
From outside the home — at least 50 feet away — call your gas utility's emergency line. Most major utilities have a dedicated 24/7 emergency number printed on every gas bill, and most will respond within 30-60 minutes for a confirmed gas smell. The dispatcher will ask whether you have already shut off the gas at the meter; if you have not, they will tell you whether to do so. If you do not know how, leave that to the responding technician.
Tip: Save your gas company's emergency line in your phone now, before you ever need it. In Southern California, that is SoCalGas at 1-800-427-2200. In Northern California, PG&E at 1-800-743-5000. Other regions: check your gas bill.
Wait for the gas company outside
The gas company will dispatch a technician with combustible-gas indicators to find the source and shut off the gas if needed. Their service is free. Wait outside until they arrive and confirm the home is safe to enter. The tech will identify whether the leak is on the utility side (their problem to fix) or on your side (an appliance or in-home gas line — a licensed appliance or plumbing tech's problem to fix). Do not re-enter until they say it is safe.
Call a licensed gas appliance technician (not a handyman)
Once the gas company has located the source as appliance-side, they will tag the appliance and shut off the supply to it. To restore service, you need a licensed gas appliance technician — not a general handyman, not a YouTube-trained DIY-er. In California, gas line work and gas appliance service requires specific licensing (C-36 for plumbing of gas lines, contractor licensing for appliance installation and service). At Axis we hold the appropriate licensing for residential gas appliance work; for new gas line installations or repipes, we coordinate with a licensed plumber.
âš Warning: Do not bypass a tagged appliance to keep using it. The tag is there because the appliance is unsafe at this moment.
After repair: confirm and test
After repair, the licensed tech will pressure-test the gas line, leak-check every fitting with bubble solution or an electronic detector, and confirm the appliance is operating correctly with a clean flame. Do not skip this verification step or accept a repair that has not been pressure-tested. Make sure your carbon monoxide detectors are working and have been replaced if older than 7 years. If you do not have a CO detector on each floor, have one installed before using the appliance again.
Tip: A combustible-gas detector for the home (separate from a CO detector) is inexpensive — $30-60 — and can give you minutes of additional warning. Worth installing in any home with gas appliances.
Brand-specific notes
Some brands have known design quirks worth knowing about before you start.
Bosch
Bosch gas tankless water heaters and ranges have safety valves on every gas-using component, so a pilot-out-with-gas-flowing situation is unusual unless a valve has failed. Smell on a Bosch usually points to a connection at the supply rather than a control issue.
GE
GE gas appliances span a wide age range — older models (pre-2000) may not have modern flame-sensing safety valves and can leak gas if a pilot blows out. Modern GE gas ranges and dryers all have flame-sense shutoff and should not leak from a pilot loss.
Wolf
Wolf gas ranges and rangetops are commercial-style with high BTU output. The flexible gas connectors behind these heavier units are often the failure point — repeated pull-out cleaning over years can stress and crack them. Annual inspection of the connector is recommended on Wolf installations.
Viking
Viking gas appliances are similar to Wolf in being heavy commercial-style units. The convection fan and oven igniter assemblies on older Vikings can develop weak ignition that allows gas to flow briefly before lighting — if you smell a brief gas puff at oven start, schedule a service call to inspect the igniter.
Whirlpool
Whirlpool gas ranges, dryers, and water heaters all use industry-standard flame-sense and pilot ignition. A persistent gas smell from a Whirlpool is more likely a connection or regulator issue than a control issue — call a tech.
What our techs see most often
When a customer calls reporting gas smell, our dispatcher's first answer is always the same: hang up, leave the house, call the gas company. We do not roll a truck to a confirmed gas leak before the gas company has shut it off — that is not how gas safety works in California. After the gas company has the leak controlled and tagged the appliance, we come out on a priority basis to repair or replace. Roughly half of the gas-smell calls we eventually service are pilot-light related on older water heaters and floor furnaces; the other half are deteriorated flexible connectors at the back of the appliance.
When to call a professional
- → You smell gas from any appliance, even faintly — call the gas company first, then a licensed gas appliance tech
- → A pilot light has gone out and you are not 100% certain about how to safely relight it (most modern appliances have automatic relight; for those that require manual relight, the procedure is on the appliance label, but if you have any doubt, call a tech)
- → You see physical damage to a gas connector — kinks, cracks, fraying, or corrosion
- → A carbon monoxide detector has alarmed (this is a separate but related emergency — leave the home, ventilate, call 911 or the gas company, and do not return until tested)
- → An appliance has been tagged or red-tagged by the gas company
- → You are renovating, moving, or replacing a gas appliance — gas line work always requires licensing
- → Any time you would otherwise be searching for a tutorial on gas line work — that is the cue to call a pro instead
Frequently asked questions
I smell gas faintly. Is it safe to keep using my appliance until I can get someone out?
No. A faint smell can mean a slow leak that is accumulating in walls, attics, or low spots in the home. The smell threshold is well below the explosive concentration but the gap can close quickly in a closed environment. Stop using the appliance, leave the home, and call the gas company. They will respond same-day for free.
Why does the smell go away after I open the windows? Was it a real leak?
Ventilation reduces the concentration but does not stop the source. If the smell came back when you closed the windows, or if it was strong at any point, it was a real leak. Even if it has cleared, have a licensed tech inspect — slow leaks at fittings can come and go with temperature and pressure cycling.
My pilot light keeps blowing out — is that the source of the smell?
Possibly. Modern gas appliances have a thermocouple or flame sensor that shuts off gas when the pilot is out, so a pilot-out should not produce a sustained gas smell. If yours does, the safety valve has failed and is allowing gas through without an active flame. That is a high-priority repair — stop using the appliance and call a tech.
Is it safe to just shut off the gas at the appliance valve and not worry about it?
Shutting off the appliance valve stops gas to that appliance, which is good. But it does not address what caused the leak in the first place — a deteriorated connector, a failed valve, a damaged regulator. Those need diagnosis and repair before the appliance is used again. The gas-off step is a holding pattern, not a fix.
How do I prevent gas leaks?
Three things. First, have all gas appliances inspected annually by a licensed tech — this catches deteriorating connectors, weak valves, and dirty burners before they fail. Second, replace flexible gas connectors every 10-15 years; older yellow-coated brass connectors are no longer code-compliant and should be replaced on sight. Third, install combustible-gas detectors and carbon monoxide detectors on each floor, replace per manufacturer schedule (CO detectors typically every 7 years).